The bank's "crime" is failing to prevent the ruble from plunging about 37% against the dollar in the last six months -- despite spending tens of billions of foreign currency reserves trying to prop it up.

It intervened in the market again this week, buying another 36.9 billion rubles ($700 million) on Monday in its first such move since allowing the currency to float freely in November.

Russia's economy was already beginning to seize up earlier this year as Western sanctions chilled investment and raised funding costs for government, banks and businesses.

The crisis has sparked a flight of capital -- some $120 billion is expected to leave the country this year. Another $80 billion could follow in 2015.

Russia has taken another big knock recently from the sharp fall in oil prices. Revenues from oil and gas make up nearly half the Russian state budget.